<i>In</i> <i>situ</i> analyzer calibration methods for heavy ion beam probes installed on stellarator-like devices

Abstract

An absolute calibration of an installed heavy ion beam probe (HIBP) energy analyzer is possible by detecting secondary ions that come from a source at a known location that is maintained at a known potential. It is also necessary that the magnetic field that exists during the calibration be the same magnetic field that exists when a plasma is present. These conditions can be met on stellarators, heliotrons, and torsatrons, which produce their magnetic configurations with external coil sets. Since no internal plasma current is required, suitable sources for producing secondary ions by interaction with the primary beam can be placed inside the vacuum vessels of these devices at known locations. Secondary ions can be produced by the interaction of the primary beam with thin films, gas box probes, electron beams, or neutral gas filling the vacuum vessel. Details of a spherical mesh probe that combines the advantages of several of these methods are given.